Wide-range oxygen sensor cell

Abstract

The utility model relates to oxygen sensor technical field, specifically disclose a wide range type oxygen sensor core body, including by upper and lower connection pump oxygen cell layer, diffusion structure layer, reference cell layer, first structure layer, heating layer and second structure layer, diffusion structure layer includes internal diffusion barrier, external diffusion barrier, external diffusion cavity and electrode reaction cavity, internal diffusion barrier is T shape structure, and it includes horizontal section and vertical section, and the middle part of vertical section is perpendicular to horizontal section and sets up, and both sides of vertical section respectively set up a external diffusion cavity, and the side away from vertical section of external diffusion cavity sets up external diffusion barrier, and electrode reaction cavity sets up in the side away from vertical section of horizontal section, one end of core body diffusion structure layer outside is provided with dip -coating protective layer. The utility model's advantage is to improve the water drop impact resistance of core body structure, and can realize exempt from dew point, and can enter closed loop control after engine starts, and it is very effective to reduce the start stage THC emission.

Description

Technical Field

[0001] This utility model relates to the field of oxygen sensor technology, and in particular to a wide-range oxygen sensor core. Background Technology

[0002] Oxygen sensors are a crucial component in engine emission control, playing a vital role in closed-loop control of the air-fuel ratio and emission optimization. Traditional on-off oxygen sensors can only indicate whether the mixture is too rich or too lean, failing to provide precise air-fuel ratio information. Wide-range oxygen sensors, on the other hand, can continuously output air-fuel ratio signals over a wider range, allowing the control system to precisely control the air-fuel ratio. This has led to their increasingly widespread use in the face of increasingly stringent emission regulations. Based on this application, practical experience has shown that emissions during engine cold starts are becoming a key area requiring control. Previous oxygen sensors, limited by structure and materials, required the sensor to reach its dew point temperature before high-power heating could be applied to initiate closed-loop air-fuel ratio control, resulting in significant THC emissions during this period. To address this issue, it is necessary to improve the water droplet impact resistance of the oxygen sensor core, allowing for direct heating without considering the dew point and earlier entry into closed-loop air-fuel ratio control.

[0003] Existing wide-range oxygen sensor cores with side air intake only have a single-stage diffusion barrier and diffusion cavity structure. In this structure, the diffusion barrier, which limits current, is designed at the edge of the core structure. On one hand, during the molding process, the diffusion barrier is cut and exposed on the surface. After firing, the two ends of the diffusion barrier along its length exhibit varying degrees of incomplete bonding of the ceramic sheets, leading to poor stability of the core's output current and performance drift after long-term service. On the other hand, the edge of the diffusion barrier is easily damaged by external mechanical forces, causing core failure. This frequently occurs during core production, and this area is also the first to crack and fail during water dripping tests. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a wide-range oxygen sensor core, which is used for precise control of the air-fuel ratio in automobile engines.

[0005] The objective of this utility model is achieved through the following technical solution: a wide-range oxygen sensor core, comprising, from top to bottom, a pump oxygen cell layer, a diffusion structure layer, a reference cell layer, a first structure layer, a heating layer, and a second structure layer. The diffusion structure layer includes an internal diffusion barrier, an external diffusion barrier, an external diffusion cavity, and an electrode reaction cavity. The internal diffusion barrier is a T-shaped structure, comprising a horizontal segment and a vertical segment. The vertical segment is disposed perpendicular to the middle of the horizontal segment. An external diffusion cavity is disposed on each side of the vertical segment. An external diffusion barrier is disposed on the side of the external diffusion cavity away from the vertical segment. The electrode reaction cavity is disposed on the side of the horizontal segment away from the vertical segment. A dip-coated protective layer is disposed on the outer side of the end of the core where the diffusion structure layer is disposed.

[0006] Specifically, the porosity of the internal diffusion barrier is less than that of the external diffusion barrier.

[0007] Specifically, the heating layer includes a heater and an insulating layer. The second structural layer is provided with heater pins, the heater is electrically connected to the heating pins, and the heater is disposed between the two insulating layers.

[0008] Specifically, the oxygen pumping battery layer includes a first substrate, an external oxygen pumping electrode, and an internal oxygen pumping electrode. The first substrate is provided with a first pin, a second pin, and a third pin. The external oxygen pumping electrode is located on the top of the first substrate and is electrically connected to the second pin. The internal oxygen pumping electrode is located inside the electrode reaction chamber and is electrically connected to the third pin.

[0009] Specifically, the reference cell layer includes a second substrate, an inner reference electrode, and an outer reference electrode. The inner reference electrode is disposed within the electrode reaction chamber and is electrically connected to a third pin. The outer reference electrode is disposed between the second substrate and the first structural layer and is electrically connected to a first pin. An electrode insulating layer is disposed between the outer reference electrode and the second substrate.

[0010] Specifically, an electrode protective layer is provided on the first substrate, and the electrode protective layer covers the oxygen pump external electrode.

[0011] This utility model has the following advantages:

[0012] The stability of the core output pump current is improved, the ignition time of the sensor is accelerated, the protection of the functional layer and heater layer is enhanced, and the water droplet impact resistance of the core structure is guaranteed. As a result, the sensor can intervene in the air-fuel ratio closed-loop control as early as possible without dew point start-up, further reducing emissions and enabling the engine to meet higher emission standards. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the overall structure of the core of this utility model;

[0014] Figure 2 This is a schematic diagram of the diffusion structure layer of this utility model;

[0015] In the figure: 1-Electrode protective layer, 2-Oxygen pumping external electrode, 3-First substrate, 4-Oxygen pumping internal electrode, 5-First pin, 6-Second pin, 7-Third pin, 8-First structural layer, 9-Second structural layer, 10-Internal diffusion barrier, 11-External diffusion barrier, 12-External diffusion cavity, 13-Electrode reaction cavity, 14-Heater, 15-Insulating layer, 16-Heating pin, 17-Second substrate, 18-Reference internal electrode, 19-Reference external electrode, 20-Electrode insulating layer, 21-Diffusion structural layer. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present utility model and are not intended to limit the present utility model; that is, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The components of the embodiments of the present utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0017] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0018] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0019] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0020] like Figures 1 to 2As shown, a wide-range oxygen sensor core includes, from top to bottom, a pump oxygen cell layer, a diffusion structure layer 21, a reference cell layer, a first structure layer 8, a heating layer, and a second structure layer 9. The diffusion structure layer 21 includes an internal diffusion barrier 10, an external diffusion barrier 11, an external diffusion cavity 12, and an electrode reaction cavity 13. The internal diffusion barrier 10 has a T-shaped structure, including a horizontal segment and a vertical segment. The vertical segment is perpendicular to the middle of the horizontal segment. An external diffusion cavity 12 is provided on each side of the vertical segment. An external diffusion barrier 11 is provided on the side of the external diffusion cavity 12 away from the vertical segment. The electrode reaction cavity 13 is provided on the side of the horizontal segment away from the vertical segment. A dip-coated protective layer is provided on the outer side of the end of the core where the diffusion structure layer 21 is located. In this embodiment, the sensor core is formed by stacking and sintering an oxygen pump cell layer, a diffusion structure layer 21, a reference cell layer, a first structure layer 8, a heating layer, and a second structure layer 9. The diffusion structure of the core is set as a multi-chamber structure, including an external diffusion chamber 12 and an electrode reaction chamber 13. Gas enters the external diffusion chamber 12 through the external diffusion barriers 11 on both sides, and then enters the electrode reaction chamber 13 from the external diffusion chamber 12 through the internal diffusion barrier 10. This improves the stability of the chip output current and the structural reliability of the atmosphere test channel. The optimized diffusion layer structure adopts a two-stage diffusion barrier and diffusion chamber design. The diffusion barrier, which plays a current limiting role, is completely surrounded inside the chip, and the output current value plateau is stable. The dip-coated protective layer is composed of water-based dip-coating material with a powder-to-liquid ratio of 1.4:1. Fine alumina accounts for 43%, coarse alumina accounts for 40%, and sintering aid accounts for 17%. It is prepared by dip-coating-drying-sintering process, with two layers prepared, each with a thickness of 0.13 mm. The sintering temperature of the dip-coated protective layer is 1050℃. The dip-coated protective layer has a porous structure and uses a material formulation and process that is much lower than the core sintering temperature. This forms a strong porous protective layer on the working end surface of the core, which significantly increases the number of water drop impacts it can withstand in the water drop test and allows the sensor to start without dew point.

[0021] Furthermore, the porosity of the internal diffusion barrier 10 is less than that of the external diffusion barrier 11. The external diffusion barrier 11 has a large porosity and mainly serves as a support to ensure unobstructed diffusion paths; the internal diffusion barrier 10 has a small porosity and mainly serves as a flow limiter.

[0022] Table 1 Material composition of diffusion barrier

[0023] Solid content carbon black Zirconia powder 1 Zirconia powder 2 External diffusion barrier ≤70% ≥60% ≤15% ≤25% Internal diffusion barrier ≥80% ≤40% ≥25% ≥35%

[0024] The dimensions of the external diffusion barrier 11 are: length ≥ 1.5 mm, width ≤ 1.5 mm, and thickness ≥ 0.05 mm.

[0025] The internal diffusion barrier 10 has the following dimensions: length ≥ 3.5 mm, width ≤ 1.2 mm, thickness ≥ 0.05 mm, and the medium particle size of the zirconia powder 1 is 1 μm-4 μm; the medium particle size of the zirconia powder 2 is 10 μm-14 μm.

[0026] Furthermore, the heating layer includes a heater 14 and an insulating layer 15. A heater pin 16 is provided on the second structural layer 9. The heater 14 is electrically connected to the heating pin 16. The heater 14 is disposed between the two insulating layers 15.

[0027] The oxygen pumping battery layer includes a first substrate 3, an oxygen pumping external electrode 2, and an oxygen pumping internal electrode 4. The first substrate 3 is provided with a first pin 5, a second pin 6, and a third pin 7. The oxygen pumping external electrode 2 is disposed on the top of the first substrate 3 and is electrically connected to the second pin 6. The oxygen pumping internal electrode 4 is disposed in the electrode reaction chamber 13 and is electrically connected to the third pin 7.

[0028] The reference battery layer includes a second substrate 17, an inner reference electrode 18, and an outer reference electrode 19. The inner reference electrode 18 is disposed within the electrode reaction chamber 13 and is electrically connected to the third pin 7. The outer reference electrode 19 is disposed between the second substrate 17 and the first structural layer 8 and is electrically connected to the first pin 5. An electrode insulating layer 20 is disposed between the outer reference electrode 19 and the second substrate 17. In this embodiment, the first substrate 3, the second substrate 17, the first structural layer 8, and the second structural layer 9 are all made of zirconium oxide material. The first structural layer 8 and the second structural layer 9 are both double-layer structures, including two zirconium oxide substrates, which can enhance the protection of the heater layer and prevent damage during the water drip test. In this example, the heater 14 is closer to the reference battery layer, shortening the ignition time of the core, so that the sensor can intervene in the air-fuel ratio closed-loop control earlier without dew point start, further reducing emissions and enabling the engine to meet higher emission standards.

[0029] Furthermore, an electrode protective layer 1 is disposed on the first substrate 3, and the electrode protective layer 1 covers the oxygen pumping external electrode 2. The electrode protective layer 1 protects the oxygen pumping external electrode 2, wherein the dip-coated protective layer is disposed on the outside of the electrode protective layer 1.

[0030] The above description is merely a preferred embodiment of this utility model and does not constitute any limitation on this utility model. Any person skilled in the art can make many possible variations and modifications to the technical solution of this utility model, or modify it into equivalent embodiments, without departing from the scope of the technical solution of this utility model. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technology of this utility model without departing from the scope of the technical solution of this utility model shall fall within the protection scope of this technical solution.

Claims

1. A wide-range oxygen sensor core, characterized in that: The core comprises, from top to bottom, a pump-oxygen battery layer, a diffusion structure layer (21), a reference battery layer, a first structure layer (8), a heating layer, and a second structure layer (9). The diffusion structure layer (21) includes an internal diffusion barrier (10), an external diffusion barrier (11), an external diffusion cavity (12), and an electrode reaction cavity (13). The internal diffusion barrier (10) is a T-shaped structure, which includes a horizontal segment and a vertical segment. The vertical segment is set perpendicular to the middle of the horizontal segment. An external diffusion cavity (12) is set on each side of the vertical segment. An external diffusion barrier (11) is set on the side of the external diffusion cavity (12) away from the vertical segment. The electrode reaction cavity (13) is set on the side of the horizontal segment away from the vertical segment. A dip-coated protective layer is set on the outer side of the core where the diffusion structure layer (21) is set.

2. The wide-range oxygen sensor core according to claim 1, characterized in that: The porosity of the internal diffusion barrier (10) is less than that of the external diffusion barrier (11).

3. The wide-range oxygen sensor core according to claim 1, characterized in that: The heating layer includes a heater (14) and an insulating layer (15). A heater pin (16) is provided on the second structural layer (9). The heater (14) is electrically connected to the heating pin (16). The heater (14) is disposed between the two insulating layers (15).

4. The wide-range oxygen sensor core according to claim 1, characterized in that: The oxygen pumping battery layer includes a first substrate (3), an oxygen pumping external electrode (2), and an oxygen pumping internal electrode (4). The first substrate (3) is provided with a first pin (5), a second pin (6), and a third pin (7). The oxygen pumping external electrode (2) is located on the top of the first substrate (3) and is electrically connected to the second pin (6). The oxygen pumping internal electrode (4) is located in the electrode reaction chamber (13) and is electrically connected to the third pin (7).

5. The wide-range oxygen sensor core according to claim 4, characterized in that: The reference cell layer includes a second substrate (17), a reference inner electrode (18), and a reference outer electrode (19). The reference inner electrode (18) is disposed in the electrode reaction chamber (13) and is electrically connected to the third pin (7). The reference outer electrode (19) is disposed between the second substrate (17) and the first structural layer (8). The reference outer electrode (19) is electrically connected to the first pin (5). An electrode insulating layer (20) is disposed between the reference outer electrode (19) and the second substrate (17).

6. The wide-range oxygen sensor core according to claim 4, characterized in that: An electrode protective layer (1) is provided on the first substrate (3), and the electrode protective layer (1) covers the oxygen pump external electrode (2).

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